The care layer is where Horses of Hoofprint Bay earns its name. The systems are small and each one is modelled on something real, and the game is unusually strict about the order in which you do them.
Brushing and feeding are the two daily basics. Brush your horses and feed them — a horse that is not groomed and fed is not going to train well, and in a management sim the daily care chore is the tax that makes attention to the bigger systems feel earned. Treat it as part of the loop rather than an interruption to it.
The standout mechanic is the hoof pick. You use it to clear debris from a horse's hoof, and doing so is what prevents saddle sores and hoof abscesses. Both of those are real equine conditions with real consequences, and both are the kind of detail that separates a horse sim that respects its subject from one that treats horses as a reskin of livestock.
The practical reading is a clean chain of cause and effect: a horse that works hard, especially under saddle, generates the conditions for sores if you skip hoof maintenance; a horse with an untreated abscess is a horse with a training setback, and in a competition-driven economy that setback costs you prize money you had already budgeted around.
Horses pick up scratches and injuries as a matter of course, and treating them is a separate step from grooming. A horse with an untreated scratch is a horse whose condition is degraded, and condition feeds into both training progress and competition eligibility. This is the other half of the care loop: grooming maintains, treatment repairs.
Because the game's economy is built on prize money and breeding value, a horse that is neglected loses value in two directions at once — it performs worse and it breeds worse. The efficient approach is to make daily care a fixed routine you can partly automate through staff, so that your attention goes to the horses that matter. That is the whole point of hiring groomers, and it is why the staff page is not an optional extra in the game's design.